The present invention relates to internal combustion engines in general, and more particularly to improvements in internal combustion engines of the type wherein several groups of cylinders can rotate discrete crankshafts. Still more particularly, the invention relates to improvements in internal combustion engines of the type having a first engine section or unit which comprises a first crankshaft adapted to be rotated by a first group of cylinders, at least one further section or unit whose crankshaft or crankshafts can be rotated by one or more additional groups of cylinders, and means for connecting the crankshafts to each other when the speed of the previously idle crankshaft or crankshafts is adequately increased to match or approximate the speed of the driven crankshaft.
It is already known to deactivate a group of cylinders in a multi-cylinder internal combustion engine when the engine is to operate at partial load. This entails substantial savings in fuel and reduces the quantity of deleterious combustion products which are discharged into the surrounding atmosphere. Reference may be had to German Offenlegungsschrift No. 28 28 298 which discloses a method of operating an internal combustion engine having several cylinders which are disposed in a common cylinder block. The engine has a composite crankshaft which includes several discrete crankshafts each associated with a given group of cylinders. When the engine is to be operated at partial load, e.g., immediately after starting, the cylinders of a first group of cylinders drive the corresponding discrete crankshaft while the remaining cylinders and the corresponding discrete crankshaft or crankshafts remain idle. If the engine is to be thereupon operated at full load, it is necessary to accelerate the remaining crankshaft or crankshafts to the speed of the crankshaft which is driven by the first group of cylinders, and to couple the crankshafts to each other only when the crankshafts assume predetermined angular positions.